Production of high molecular weight aromatics



July 15, 1958 H. G. CORNEIL ET AL PRODUCTION OF HIGH MOLECULAR WEIGHT AROMATICS I FEED A sues TANT/AL LY PURE cmL/c HYDHOCARBO/VS Filed July 15, 1954 DEASPl-IA LT/NG ZONE OIL 2/3 DEASPHALTED DIST/LLATION ZONE DIS T/LL AT/OIV ZONE ASPHALT FRACTION Hampton G Edward F. Wad/ey,

w/ww FRACTION BOILING ABOVE 650 5 IN V EN TORS. Come/l,

A TTOR/VE).

United States Patent PRODUCTION or HIGH MOLECULAR WEIGHT AROMATICS 1 Hampton G. Corueil and Edward F. Wadley, Baytowu,

Tex., assignors, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. 1., a corporation of Delaware Application July 15 1954, Serial No. 443,476

3 Claims. (Cl. 196-52) This application is directed to a method for securing a fraction consisting of high boiling cyclic compounds.

The objects and advantages of the present invention will be seen from the following description taken with the drawing in which the sole figure is in the form of a diagrammatic flow sheet.

Turning now specifically to the drawing, a feed tank 11 contains a charge stock. The charge stock is a gas oil boiling above 430 F. derived from petroleum. The charge stock is passed from tank 11 through line 12 to a catalytic cracking step 13. In the drawing the step is shown schematically as a single unit. It will be understood that in actual operation it is usual to provide several units for performing this step. In general, the step of catalytically cracking the feed stock involves heating the oil in the presence of a cracking catalyst. Cracking catalysts are well known to the art. By way of specific examples illustrating such catalysts may be mentioned silica-alumina or silica-magnesia, silica-zirconia and the like. The cracking reaction may take place at a temperature within the range of about 800 to 1100 F. with a preferred range of about 900 to 1000 F.

The product from the catalytic cracking step 13 is passed by line 14 to a distillation step 15. The distillation step is shown as performed in a single vessel. It will be understood that instead of a single vessel two or more vessels may be employed, if desired. In the distillation step a low boiling fraction is removed through outlet line 16, a fraction boiling above 650 F. is removed as a side stream through line 17 and the bottoms fraction is withdrawn through line 18. The side stream fraction boiling above about 650 F. is passed to a propane deasphalting step 19.

In the propane deasphalting step 19, liquefied normally gaseous hydrocarbon, for example, propane or butane or mixtures of propane and butane, is contacted with the distillate fraction under suitable conditions to separate an asphalt fraction and a lighter oil-containing fraction. The step of deasphalting an oil to separate it into an asphalt fraction and a deasphalted oil fraction is well known to the art. While a single rectangle is shown in the drawing, several vessels, including settling vessels and stills to receive the solvent may be used. By way of example as to operating conditions for the deasphalting step, it may be stated that a solvent to oil ratio within the range of 1:1 to :1 and a temperature within the range of 50 to 250 F. may be used. The deasphalted oil fraction is removed through line 21 and the asphalt fraction is removed through line 22. The asphalt fraction is charged to a second distillation zone 23 where it is separated into an overhead fraction removed through line 24 and consisting of practically nothing but cyclic hydrocarbons and a heavy bottoms fraction which is withdrawn through outlet line 25.

The overhead withdrawn through line 24 is the desired product of the process. It consists of substantially pure cyclic hydrocarbons and is suitable for use as a raw 2,843,531 Patented July 15, 1958 material in chemical processes, as a wood preserver, plasticizer or for many other uses.

' The practice of the present invention will now be illustrated by way of a specific example. A distillate fraction boiling above 650 F. was obtained by catalytically cracking a gas oil feed stock at a temperature of approximately 930 F. in the presence of a silica-alumina catalyst, and then distilling the product to recover a distillate fraction boiling above 650 F. This distillate fraction was deasphalted in the deasphalting unit using propane as the solvent and a solvent oil volume ratio of 1.5/1 with the deasphalting step conducted in a countercurrent tower having a top temperature of 190 F. and a bottom temperature of F. From the deasphalting step a yield of 80.4% deasphalted oil and 19.6% of asphalt was obtained. The asphalt fraction was distilled with the results of the distillation as follows:

Table I Based on charge to deasphalting step 0-25% overhead from vacuum distillation of asphalt 4.9 25-4-6% overhead from vacuum distillation of asphalt 4.1 Total overhead from vacuum distillation of asphalt 9.0 Bottoms from vacuum distillation of asphalt 10.6

The material charged to the deasphalting step, the deasphalted oil fraction, the asphalt fraction and the distillates obtained by the vacuum distillation of the asphalt fraction had the characteristics as follows:

Table II Dlstillates from Vacuum Distillatlon of Deas- Asphalt Product Quality Data-0ll Charge phgliped Asphalt Over- Overhead head Gravlty, API 11.9 19. 2 -10. 5 5. 8 8.7 Aniline Point, F 136 15 4 Aromatics by Silica Gel,

Wt. percent 57.0 46 68. 2 98. 0 98.8 Aromatics Index 55.0 37 100 Naphthene Index 2. 0 0 0 0 Conradson Carbon, Wt.

percent 6. 7 1. 5 20. 3 3. 2 11.0 ASTM 10 mm. Distillation:

fin 740 741 825 50% 846 853 80% 918 From this example it can be seen that whereas the asphalt fraction obtained from the deasphalting step contained only 68.2% aromatics, the distillates secured by the vacuum distillation of the asphalt consisted of 98.0% and 98.8% aromatics. Thus by following the method of the present invention a substantially pure aromatics fraction may be obtained.

What we desire to claim as our invention is:

1. A method for preparing a fraction consisting essentially of cyclic compounds including the steps of catalytically cracking a petroleum gas oil fraction at a temperature within the range of about 800 to 1100 F. to produce a product, distilling said product to separate therefrom a distillate fraction boiling above 650 F., contacting a charge stream consisting of said distillate fraction with liquefied normally gaseous hydrocarbon to separate an asphalt fraction therefrom containing cyclic and non-cyclic components and distilling a charge stream consisting of said separated asphalt fraction to recover 3 a distillate fraction consisting essentially of cyclic compounds.

2. A method for preparing a fraction consisting essentially of cyclic compounds including the steps of catalytically cracking a petroleum gas oil fraction at a temperature within the range of about 800 to 1100 F. boiling above 650 F. to produce a product, distilling the product to separate a distillate fraction boiling above 650 F., admixing a charge stream consisting of said distillate fraction with liquefied normally gaseous hydrocarbon solvent at a solvent to oil ratio within the range of 1:1 to 5:1 by volume and at a temperature within the range of 50 F. to 250 F. to separate an asphalt fraction containing cyclic and non-cyclic components and distilling a charge stream consisting of said separated asphalt fraction to recover a distillate fraction consisting essentially of cyclic compounds.

3. A method for preparing a fraction consisting essentially of cyclic compounds including the steps of catalytically cracking a petroleum gas oil fraction at a temperature within the range of about 800 to 1100 F. to produce a product, distilling the product to separate a distillate fraction boiling above 650 F., admixing a charge stream consisting of the said distillate fraction with liquefied normally gaseous hydrocarbon solvent at a solvent to oil ratio within the range of 1:1 to 5:1 by volume and at a temperature Within the range of 50 F. to 250 F. to separate an asphalt fraction containing aromatic and non-aromatic components and vacuum distilling a charge stream consisting of said asphalt fraction to recover a distillate fraction consisting essentially of aromatic compounds, said thus obtained aromatics distillate fraction consisting of less than about 50 percent of said asphalt charge stock.

References Cited in the file of this patent UNITED STATES PATENTS Knox Jan. 25, 1955 Love et a1 Jan. 17, 1956 OTHER REFERENCES 

1. A METHOD FOR PREPARING A FRACTION CONSISTING ESSENTIALLY OF CYCLIC COMPOUNDS INCLUDING THE STEPS OF CATALYTICALLY CRACKING A PETROLEUM GAS OIL FRACTION AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 800* TO 1100*F. TO PRODUCE A PRODUCT, DISTILLING SAID PRODUCT TO SEPARATE THEREFROM A DISTILLATE FRACTION BOILING ABOVE 650*F., CONTACTING A CHARGE STREAM CONSISTING OF SAID DISTILLATE FRACTION WITH LIQUEFIED NORMALLY GASEOUS HYDROCARBON TO SEPARATE AN ASPHALT FRACTION THEREFROM CONTAINING CYCLIC AND NON-CYCLIC COMPONENTS AND DISTILLING A CHARGE STREAM CONSISTING OF SAID SEPARATED ASPHALT FRACTION TO RECOVER A DISTILLATE FRACTION CONSISTING ESSENTIALLY OF CYCLIC COMPOUNDS. 